To some extent, I believe it would matter on the actions you took in the game. Perhaps the ending(s?) are reflective of this. Maybe, if this information is true, you have at points the possibility of forming a brief alliance with them to take down something bigger than yourselves, the Big Sister coming to mind. Maybe whether or not, similar to BS1, how you choose effects their fate in the ending? I doubt Abbott really cares for Rapture all that much himself, all he wants is the kid (his daughter?) back. I think it likely forming alliances could potentially be a part of the next game too; if this info is all true, the Telepathy plasmid suggests a great deal of NPC interaction in the game.
It doesn't really matter to me, mind you, I don't really want Soviet agents in all that much either; just looking for ways to make their presence, if it's inevitable, an interesting one.
As someone else noted, while it's doubtful pets were truly widespread in Rapture (no matter how many dead cats you see in BS1

), it's very likely preliminary ADAM tests were on animals. If the info is true, the test subjects were probably dogs.
As for the squid, possible that she's been eating the sea slugs all her life...and that's why she's gotten so big; the squid might have had its metabolism slowed down to the point of near biological immortality or something (hence why it's so frigging big).